The present invention relates to the field of processing information presented by optical signals, in particular to optical logic, amplification and optical signal commutation devices having semiconductor structures. The preferable field of use is for fiber-optical communications and information transmission systems, integral optic and computer engineering circuits.
A "Nonlinear interferometer" (U.S. Pat. No. 3,813,609, 1969) device is known, which makes it possible to obtain a two-valued hydteretic relationship between the output power of optical radiation and the input power. This characteristic can be converted to the single-value relationship of differential amplifier by the initial detuning of a Fabry-Perot resonator. The main member of this device, a nonlinear saturable absorber, the index of which changes with the intensity of incident radiation, brightens when a certain threshold of light intensity is exceeded. Experimental research has been conducted on the possibility of realizing optical devices in logic elements of a memory.
The use of dielectric material as the working medium requires large pump power (10.sup.8 W/cm.sup.2), i.e. the use of powerful lasers, because of the small nonlinearity factor of that material.
Furthermore, fixed tuning of the resonator to a frequency and the absence of a control voltage on the dielectric crystal eliminate the possibility of changing the wave length of the output radiation. This determines the field of use of the device--for laboratory research on the bistable effect. On the other hand, at present there is no engineering solution for an integral optical combination of a semiconductor laser and a dielectrical element. These reasons provide an obstracle for practical realization of this device.
A "Bistable integral optical device" is known (see, for example, French Patent No. 2464498), in which directional couplers are encompassed by positive electrical feedback so that a bistable mode is realized in the device. Advantages of this device are its small size, the possibility for integral realization with a high degree of isolation between the forward and alternative channels. Drawbacks are absence of the possibility for changing the frenquency of the output radiation, the necessity for using a photodetector and an amplifier with a nonlinear response in the feedback circuit, which is a consequence of using electrical feedback in that device.
The device among the known devices which is closest with respect to technical substance to the proposed device is that produced by the "Hughes Aircraft" company (E.A.J. Marcatili "Bends in Optical Dielectric Guides", The Bell System Technical Journal, vol. 48, No. 7, 1969, 2103-2132). The device is an optical gate, selecting the radiation of a different frequency over channels: that frequency is selected from three frequencies, propagating along a waveguide optically coupled to a nonlinear resonant ring, which corresponds to the resonant frequency to which the ring is tuned, that frequency is radiated and switching accomplished.
An advantage of this device is its compact size and the use of resonant rings as integral logic elements. Wherein, the resonant rings are made with a high Q-factor (0-10.sup.8) and with a difference in the indexes of refraction of the waveguide and the environment at 0.01% of the radius of the ring P equal to 0.04-1 mm.
Drawbacks of this device are: the absence of an external pump source for optical radiation to initiate the nonlinear effects when fixing low level signals; the absence of full access and reciprocity between the optical contacts; the absence of the possibility for changing the wave length of output radiation and the tuning of the resonant ring; the substantial power level of the input signals necessary to excite the nonlinear effects in the resonant ring using the energy of those same input pulses, which is a consequence of the absence of input pulses and the absence of active members inside the system itself; there is no restoration of signal power loss.